1. Field of Invention
The present invention relates to fluid pumps. More particularly, the present invention relates to diaphragm and piston pumps wherein the pump chamber working volume varies due to deformation and/or displacement of a diaphragm or piston member, and wherein the diaphragm or piston member either comprises or is acted upon by a piezoelectric element which deforms when electrically energized.
2. Description of the Prior Art
Diaphragm pumps are a very well known form of positive displacement reciprocating pump. Diaphragm pumps typically comprise a pump chamber, an inlet valve which opens the chamber to an inlet pipe during the suction stroke, an outlet valve, which opens to a discharge pipe during the discharge stroke, and a diaphragm drive mechanism. The pumping action is developed through the alternating filling and emptying of the pump chamber caused by the reciprocating motion of the diaphragm member which varies the confining work volume of the pump chamber.
In prior diaphragm pumps the reciprocating motion of the diaphragm member is typically accomplished by attaching the diaphragm member to a connecting rod which in turn is connected to a rotating crank, or by an equivalent mechanical transmission system. The power to the rotating crank is typically provided by internal combustion-driven piston(s), by steam-driven piston(s), by electric motor, or by equivalent mechanisms.
A problem associated with such prior diaphragm pumps is that, owing in part to the complex nature of the connecting rod, the rotating crank and the mechanical power source, they are relatively heavy.
Another problem associated with such prior diaphragm pumps is that, owing in part to the complex nature of the connecting rod, the rotating crank and the mechanical power source, they are relatively expensive.
Another problem associated with such prior diaphragm pumps is that, owing in part to the complex nature of the connecting rod, the rotating crank and the mechanical power source, they have numerous components which are susceptible to wearing out, and are relatively costly to maintain.
Another problem associated with such prior diaphragm pumps is that, owing in part to the complex nature of the connecting rod, the rotating crank and the mechanical power source, is that they are of relatively low power conversion efficiency.
Another problem associated with such prior diaphragm pumps is that, owing in part to the nature of the connecting rod, the rotating crank and the mechanical power source, is that the discharge pressure and flow rate are not readily adjustable and are not independently controllable.
Another problem associated with such prior diaphragm pumps is that the mechanical power source which drives the diaphragm member is, in most embodiments, not immersible in liquids, particularly in volatile liquids.
Another problem associated with many such prior diaphragm pumps is that in order to stop discharge the pump must be (electrically or mechanically) disconnected from its power supply.
Another problem associated with many such prior diaphragm pumps is that, owing in part to the complex nature and relative inefficient energy conversion properties of the connecting rod, the rotating crank and the mechanical power source, they have a tendency to overheat unless provided with supplemental heat sinking materials.
Another problem associated with such prior diaphragm pumps is that they are frequently difficult to prime.
Another problem associated with such prior diaphragm pumps is that fluid is discharged in discontinuous spurts, the volume and frequency of which spurts, is typically non-adjustable and dependent upon the nature of the driving power supply.
Another problem associated with prior diaphragm pumps is that the controlled expansion and contraction of the volume of the pump chamber, the controlled valving of the fluid inlet, and the controlled valving of the fluid outlet are accomplished by at least three separate components of the device, each of which is dedicated to the performance of its singular task. Accordingly, such prior devices have multiple parts which are susceptible to wearing out, and which require maintenance, and which increase the cost of the device. In addition, the movement of these various components must be controlled so as to ensure the proper sequencing of their operations. While the proper timing/sequencing of operation of the inlet valve, the outlet valve, and the diaphragm member are readily controlled during relatively low frequency operation, at extremely high frequency pumping operations it is more difficult to ensure the proper sequencing of the three mentioned components.